OTTAWA—The federal auditor general says Montreal’s new Champlain Bridge will cost more than forecast and won’t be ready on time.

Michael Ferguson says in his annual spring report the scheduled Dec. 21 opening of the bridge appears to be ambitious, even with additional new resources or the use of new construction methods to speed up its completion.

Ferguson is also taking issue with Ottawa, saying the federal government should have moved ahead earlier on the project.

He says the dilly-dallying has cost taxpayers more than $500 million, including $306 million in major repair work done on the current Champlain Bridge, which links Montreal with its south shore.

The half-billion dollars also includes a special additional payment of $235 million to be given to the SNC Lavalin-led consortium overseeing the project, which originally had a budget of $4.2 billion.

Ferguson says work on the bridge has also been delayed by labour conflicts and snafus in the delivery of parts.

The auditor general says the decision to use a public-private partnership with the goal of saving money was done without an analysis.

Considered one of Canada’s busiest bridges with roughly 50 million crossings yearly, the current 56-year-old structure has been deteriorating for years.

Upon completion of the project, the consortium will maintain and operate the new bridge for 30 years.